Sabine Zundel

Flagellin Induces Myeloid-Derived Suppressor Cells: Implications for Pseudomonas aeruginosa Infection in Cystic Fibrosis Lung Disease

Pseudomonas aeruginosa persists in patients with cystic fibrosis (CF) and drives CF lung disease progression. P. aeruginosa potently activates the innate immune system, mainly mediated through pathogen-associated molecular patterns, such as flagellin. However, the host is unable to eradicate this flagellated bacterium efficiently. The underlying immunological mechanisms are incompletely understood. Myeloid-derived suppressor cells (MDSCs) are innate immune cells generated in cancer and proinflammatory microenvironments and are capable of suppressing T cell responses. We hypothesized that P. aeruginosa induces MDSCs to escape T cell immunity. In this article, we demonstrate that granulocytic MDSCs accumulate in CF patients chronically infected with P. aeruginosa and correlate with CF lung disease activity. Flagellated P. aeruginosa culture supernatants induced the generation of MDSCs, an effect that was 1) dose-dependently mimicked by purified flagellin protein, 2) significantly reduced using flagellin-deficient P. aeruginosa bacteria, and 3) corresponded to TLR5 expression on MDSCs in vitro and in vivo. Both purified flagellin and flagellated P. aeruginosa induced an MDSC phenotype distinct from that of the previously described MDSC-inducing cytokine GM-CSF, characterized by an upregulation of the chemokine receptor CXCR4 on the surface of MDSCs. Functionally, P. aeruginosa–infected CF patient ex vivo–isolated as well as flagellin or P. aeruginosa in vitro–generated MDSCs efficiently suppressed polyclonal T cell proliferation in a dose-dependent manner and modulated Th17 responses. These studies demonstrate that flagellin induces the generation of MDSCs and suggest that P. aeruginosa uses this mechanism to undermine T cell–mediated host defense in CF and other P. aeruginosa–associated chronic lung diseases.

Neutrophilic myeloid-derived suppressor cells in cord blood modulate innate and adaptive immune responses

Neonates show an impaired anti‐microbial host defence, but the underlying immune mechanisms are not understood fully. Myeloid‐derived suppressor cells (MDSCs) represent an innate immune cell subset characterized by their capacity to suppress T cell immunity. In this study we demonstrate that a distinct MDSC subset with a neutrophilic/granulocytic phenotype (Gr‐MDSCs) is highly increased in cord blood compared to peripheral blood of children and adults. Functionally, cord blood isolated Gr‐MDSCs suppressed T cell proliferation efficiently as well as T helper type 1 (Th1), Th2 and Th17 cytokine secretion. Beyond T cells, cord blood Gr‐MDSCs controlled natural killer (NK) cell cytotoxicity in a cell contact‐dependent manner. These studies establish neutrophilic Gr‐MDSCs as a novel immunosuppressive cell subset that controls innate (NK) and adaptive (T cell) immune responses in neonates. Increased MDSC activity in cord blood might serve as key fetomaternal immunosuppressive mechanism impairing neonatal host defence. Gr‐MDSCs in cord blood might therefore represent a therapeutic target in neonatal infections.

Perioperative Outcome of Patients with Esophageal Atresia and Tracheo-esophageal Fistula Undergoing Open Versus Thoracoscopic Surgery

INTRODUCTION Thoracoscopic approach for repair of esophageal atresia (EA) and tracheo-esophageal fistula (TEF) has become a standard procedure in many pediatric surgical centers. Thoracoscopic surgery in a newborn is demanding from both the surgeon and the patient. The potential benefits for the newborn are still discussed by neonatologists, pediatric intensive care physicians, and also parents. The aim of our investigation was to clearly define perioperative outcome and complication rates in children undergoing thoracoscopic versus open surgery for EA and TEF repair. PATIENTS AND METHODS We reviewed the records of 68 newborns undergoing surgery for EA and TEF between March 2002 and February 2010. Patient data of open versus thoracoscopic approach were compared regarding operating time, intraoperative as well as postoperative pCO(2)max values, postoperative ventilation time, and complications. Specific patient data are reported with the median and range. Data analysis was done with the JMP(®) 7.0.2 statistical software (SAS Institute, Cary, NC). RESULTS For the 68 patients, the mean gestational age was 35 weeks (28-41), the median birth weight was 2720 g (1500-3510 g) in the thoracoscopic group and 2090 g (780-3340 g) in the open group. There were 36 girls and 32 boys. Thirty-two children had associated anomalies. Twenty-five children were undergoing a thoracoscopic procedure. In 8 cases, the operation was converted to open thoracotomy. Another 32 children received a thoracotomy. In 11 newborns, a cervical esophagostomy was performed because of long-gap EA and these patients were excluded from the study. Operating time was 141 minutes (77-201 minutes) in the thoracoscopic group and 106 minutes (48-264 minutes) in the thoracotomy group, with significant difference (P=.014). Values of pCO(2)max during operation were 62 mm Hg (34-101 mm Hg) in the thoracoscopic group and 48 mm Hg (28-89 mm Hg) in the open group, with significant difference (P=.014). Postoperative ventilation time was 3 days (1-51 days) in all groups, with no significant difference (P=.79). Early complications were noticed in 9 children undergoing thoracoscopy and in 8 patients of the thoracotomy group, again with no significant difference (P>.05). CONCLUSION Thoracoscopic repair of EA with TEF is justified because of a comparable perioperative outcome to open surgery, competitive operating times, decreased trauma to the thoracic cavity, and improved cosmesis despite skeptical considerations. Complication rates are not higher than in children operated on through a thoracotomy. However, a learning curve has to be taken into account and large experience in minimal invasive surgery is mandatory for this procedure. Larger series have to be expected for a more objective evaluation of perioperative as well as long-term outcomes. To our opinion, the thoracoscopic approach appears to be favorable and could be a future standard.

Regulatory T-cell impairment in cystic fibrosis patients with chronic pseudomonas infection.

RATIONALE Patients with cystic fibrosis (CF) lung disease have chronic airway inflammation driven by disrupted balance of T-cell (Th17 and Th2) responses. Regulatory T cells (Tregs) dampen T-cell activation, but their role in CF is incompletely understood. OBJECTIVES To characterize numbers, function, and clinical impact of Tregs in CF lung disease. METHODS Tregs were quantified in peripheral blood and airway samples from patients with CF and from lung disease control patients without CF and healthy control subjects. The role of Pseudomonas aeruginosa and CF transmembrane conductance regulator (CFTR) in Treg regulation was analyzed by using in vitro and murine in vivo models. MEASUREMENTS AND MAIN RESULTS Tregs were decreased in peripheral blood and airways of patients with CF compared with healthy controls or lung disease patients without CF and correlated positively with lung function parameters. Patients with CF with chronic P. aeruginosa infection had lower Tregs compared with patients with CF without P. aeruginosa infection. Genetic knockout, pharmacological inhibition, and P. aeruginosa infection studies showed that both P. aeruginosa and CFTR contributed to Treg dysregulation in CF. Functionally, Tregs from patients with CF or from Cftr(-/-) mice were impaired in suppressing conventional T cells, an effect that was enhanced by P. aeruginosa infection. The loss of Tregs in CF affected memory, but not naive Tregs, and manifested gradually with disease progression. CONCLUSIONS Patients with CF who have chronic P. aeruginosa infection show an age-dependent, quantitative, and qualitative impairment of Tregs. Modulation of Tregs represents a novel strategy to rebalance T-cell responses, dampen inflammation, and ultimately improve outcomes for patients with infective CF lung disease.

Acute traumatic posterior elbow dislocation in children

Traumatic posterior dislocation of the elbow is often associated with significant morbidity and incomplete recovery. The aim of this study was to retrospectively analyse the outcome of 33 children (median age 10.8 years). Patients underwent reduction and assessment of stability under general anaesthesia. Pure dislocations (n=10) were immobilized, whereas unstable fractures (n=23) were stabilized. Refixation of ligaments was performed if stability was not achieved by fracture stabilization alone. Immobilization was continued for 26 (pure dislocations) or 35 days (associated injuries), respectively. Results were excellent (n=9) or good (n=1) after pure dislocation. Results were excellent (n=15), good (n=7) or poor (n=1) in children with associated injuries. Accurate diagnosis, concentric stable reduction of the elbow as well as stable osteosynthesis of displaced fractures are associated with good results in children with acute posterior elbow dislocations.

Diagnosis and Treatment of Pediatric Necrotizing Fasciitis: A Systematic Review of the Literature

Introduction Pediatric necrotizing fasciitis (NF) is a rare but severe, life‐threatening infection. Early diagnosis is crucial to reduce morbidity and mortality, but initial symptoms are nonspecific. Little sound data exists on factors aiding clinicians to recognize NF in children. With a systematic literature review, we aimed to better characterize pediatric NF. We focused on triggers, symptoms, and laboratory and microbiological findings and differences between pediatric adult patients. Materials and Methods A literature research was conducted according to the guidance of the “Preferred Reporting Items for Systematic Reviews and Meta‐Analyses.” Articles published between January 2010 and October 2015 were included. Data extraction was performed as an iterative process. Results A total of 32 articles describing 53 pediatric patients with NF were included in the analysis. Overall mortality was 15.4%. Frequency peaks were found for neonates and children aged between 1 and 2 years. These two age groups were predominantly affected on the torso. Another frequency peak was found in patients aged around 10 years of age. These patients were predominantly affected on the extremities and face. In general, early symptoms were found to be fever, erythema, localized selling, and tenderness or pain. “Pain out of proportion” was not mentioned as a typical symptom. Fever and leukocytosis were more common in teenage patients. Monomicrobial necrotizing (type 2) fasciitis was much more common than polymicrobial (type 1) fasciitis. Next to Streptococci and Staphylococci, Pseudomonas aeruginosa was often isolated. Early aggressive surgical treatment was the treatment of choice. Conclusions Pediatric NF has distinguishing features that differ from adult NF. Knowledge of these details should increase early diagnosis and improve treatment.

Serum Concentrations of Interleukin-6, Procalcitonin, and C-Reactive Protein: Discrimination of Septical Complications and Systemic Inflammatory Response Syndrome after Pediatric Surgery.

BACKGROUND Early differentiation between sepsis and systemic inflammatory response syndrome (SIRS) is useful for therapeutic management in neonates and infants after surgery. OBJECTIVE To compare the early (first 2 days) diagnostic value of interleukin-6 (IL-6), procalcitonin (PCT), and C-reactive protein (CRP) after surgery in the differentiation of subsequent SIRS and septic complications. METHODS IL-6, PCT, and CRP were measured 0, 24, and 48 hours after surgery in neonates and infants with clinical suspicion of postoperative sepsis. Sensitivity, specificity, and predictive values for SIRS/septic complications were calculated. RESULTS A total of 31 out of 205 neonates and infants showed clinical signs for postoperative sepsis and underwent sepsis work-up. Nine patients developed septic complications, sixteen patients met criteria for SIRS, and six patients showed an uneventful postoperative course during the first five postoperative days. IL-6, PCT, and CRP levels increased in all subgroups after surgery and were significantly higher in the sepsis group (p < 0.05). IL-6 peaked immediately, CRP at 24 to 48 hours, and PCT at 24 hours after surgery. Sensitivity and specificity (area under the curve) for IL-6 (cutoff 673 ng/dL) were 94.4 and 75% (86.2%), for CRP (cutoff 1.48 mg/dL) 76.2 and 75.0% (88.1%), and for PCT (cutoff 16.1 mg/L) 66.7 and 57.1% (65.6%). CONCLUSION IL-6 appears to be an early marker for severe bacterial infections with high sensitivity. IL-6 and CRP were the most reliable markers for the discrimination between SIRS and sepsis within the postoperative period.

Portfolios Enhance Clinical Activity in Surgical Clerks

OBJECTIVES A change in German licensing legislation imposed a portfolio for surgical clerks. We aimed to analyze whether the implementation of the portfolio changed the amount of clinical exposure and activities during surgical clerkships. DESIGN The study was conducted with a modified pre-post design at the University Hospital of Tuebingen, Germany. Before and after the implementation of the portfolio on April 1, 2013, final-year students (n = 557) who had just finished their surgical clerkship were interviewed with an online questionnaire. A total of 21 basic surgical skills were evaluated. RESULTS Overall, 230 questionnaires were returned and analyzed; 51% were preintervention. Overall clinical activity for the whole study cohort varied for different activities between 98% and 32%. For 16 of 21 parameters, there was more clinical activity in the postintervention (portfolio) group. This difference was statistically significant for the following 7 activities: discharge, analgesia, local infiltration, patient positioning, drain in, blood transfusion, and emergency diagnostics. CONCLUSION The implementation of the portfolio did enhance clinical activity for surgical clerks in the study cohort. Nevertheless, overall exposure is still unsatisfactory low for some activities. Additional changes and studies are necessary to further improve surgical education.

Behandlungsstrategien bei Verletzungen von Milz und Leber im Kindesalter

Traumatic injuries of the spleen and liver are typically caused by age-related falls or sports and traffic accidents. Today, the non-operative management for isolated injuries is established and evidence-based guidelines are available. The intact abdominal wall and the limited space within the peritoneum produce a compression which is the pathophysiological explanation for the limitation of the haemorrhage. Precondition for the non-operative therapy is the radiology-based classification of the injury (organ injury scale) and a haemodynamically stable patient. Haemodynamic stability is, if necessary maintained with blood transfusion, volume substitutes and the administration of catecholamines. In cases of hilar vascular injury and devascularisation or haemodynamic instability of the patient, despite utilisation of the measures mentioned above, urgent operative therapy needs to be performed. Organ sparing surgery is the therapy of choice for both liver and spleen. The spleen is required for the development of a competent immune system in the growing organism. Liver injuries can be further complicated by injury to the bile system, which might require operative reconstruction. If a patient suffers from multiple injuries and spleen or liver are involved, the decision on the management needs to be taken individually, no guidelines exist but the rate for operative therapy increases. Independent of the dimensions of injury, an experienced paediatric surgeon with his multidisciplinary team, considering the anatomic and age specific characteristics of a child, achieves the best therapeutic results.

Pediatric Necrotizing Fasciitis: Restitutio Ad Integrum after Early Diagnosis and Aggressive Surgical Treatment

Necrotizing fasciitis (NF) is a severe, life-threatening infectious condition. Diagnosis is difficult due to unspecific symptoms yet crucial for favorable outcomes. We report a case of a 1 year old, previously healthy boy, where early suspicion of NF led to prompt aggressive therapy and consecutive restitutio ad integrum.